Method for preparing a mold part useful for transferring a coating onto an optical substrate

Abstract

This invention relates to a method for preparing at least one mold part of a two-part mold useful for transferring a hydrophobic top coat from a mold onto an optical substrate. Further, the invention relates to a method for easily transferring a hydrophobic top coat from a mold onto the anti-reflecting coating of a coated optical substrate. Additionally, the invention relates to a method which provides improved adhesion of the hydrophobic top coat onto an optical substrate and in particular onto an anti-reflecting coating of a coated optical substrate. The invention also discloses a mold part useful in such methods.

1. A method for preparing at least one mold part of a two-part mold which comprises:
 (a) providing a two-part mold having opposed optical surfaces intended to define therebetween a molding cavity;  
 (b) forming a hydrophobic top coat on the optical surface of at least one of the mold parts; and  
 (c) forming an anti-reflecting coating onto the hydrophobic top coat;  
 
       wherein, the anti-reflecting coating comprises a stack of dielectric material layers of alternate high and low refractive indices, and the first dielectric material layer deposited on the hydrophobic top coat is deposited using a two stage process in which, in a first stage, a first sub-layer of dielectric material is deposited by vacuum deposition and, thereafter, in a second stage, a second sub-layer is deposited by ion assisted vacuum deposition. 
     
     
       2. The method of  claim 1 , wherein said at least one mold part is made of a plastic material. 
     
     
       3. The method of  claim 2 , wherein the mold part is a flexible mold part. 
     
     
       4. The method of  claim 1 , wherein the layers of the stack are vacuum deposited. 
     
     
       5. The method of  claim 1 , wherein the first dielectric material is SiO 2 . 
     
     
       6. The method of  claim 1 , wherein the thickness of the first sub-layer ranges from 2 to 12 nm and the thickness of the second sub-layer ranges from 68 to 98 nm. 
     
     
       7. The method of  claim 1 , wherein the stack of dielectric material layers is a four layer SiO 2 /ZrO 2 /SiO 2 /ZrO 2  stack. 
     
     
       8. The method of  claim 1 , further comprising the step of forming an additional SiO 2  layer onto the anti-reflecting coating for promoting adhesion to a scratch-resistant coating. 
     
     
       9. The method of  claim 8 , wherein said additional SiO 2  layer has a physical thickness ranging from 1 to 50 nm. 
     
     
       10. The method of  claim 1 , further comprising, prior to step (b), a step of forming a protective coating on the optical surface of the mold part. 
     
     
       11. The method of  claim 10 , wherein the protective coating is a UV cured acrylic layer, an amine containing polysiloxane layer, a fluorocarbon polymer layer, or a vacuum deposited magnesium fluoride layer. 
     
     
       12. The method of  claim 1 , wherein the hydrophobic top coat is made of a silicone or a fluorosilicone. 
     
     
       13. The method of  claim 1 , wherein the hydrophobic top coat has a thickness ranging from 2 to 15 nm. 
     
     
       14. The method of  claim 1 , wherein the mold part is made of a plastic material comprised of polycarbonates, polyamides, polyimides, polysulfones, copolymers of polyethylene terephtalate and polycarbonate, crystal polyethylene terephtalate, glass fiber reinforced polyethylene terephtalate, and/or polynorbornenes. 
     
     
       15. The method of  claim 1 , wherein the plastic material is polycarbonate. 
     
     
       16. The method of  claim 1 , wherein the plastic material of the mold part comprises a release agent. 
     
     
       17. The method of  claim 16 , wherein the release agent is trimethylchlorosilane, chloromethyltrimethylsilane, chloropropyltrimethylsilane, chloromethyl dodecyidimethylsilane, chlorine terminated polydimethylsiloxane, (3,3-dimethylbutyl)dimethylchlorosilane, hexamethyldisilazane, octamethylcyclotetrasilozane, aminopropyidimethyl terminated polydimethylsiloxane, 3-trimethoxysilyl propyl octadecyl dimethylammonium chloride, tetradecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, trimethylethoxysilane, or octadecyltrimethoxysilane. 
     
     
       18. The method of  claim 1 , further comprising forming a scratch-resistant coating onto the anti-reflecting coating. 
     
     
       19. The method of  claim 18 , wherein the scratch-resistant coating is formed by curing a composition comprising as main constituents an epoxyalkoxysilane, a dialkyldialkoxysilane, and colloidal silica or a hydrolyzate thereof. 
     
     
       20. The method of  claim 19 , wherein the scratch-resistant coating composition further comprises an effective amount of a coupling agent which is a pre-condensed solution of an epoxyalkoxysilane and an unsaturated alkoxysilane. 
     
     
       21. The method of  claim 20 , wherein the epoxyalkoxysilane is γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylpentamethyldisiloxane, γ-glycidoxypropylmethyldiisopropenoxysilane, (γ-glycidoxypropyl)methyldiethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyidiisopropylethoxysilane, or (γ-glycidoxypropyl)bis(trimethylsiloxy)methylsilane. 
     
     
       22. The method of  claim 20 , wherein the unsaturated alkoxysilane is tris(2-methoxyethoxy)silane, vinyltrisisobutoxysilane, vinyltri-t-butoxysilane, vinyltriphenoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldiethoxysilane, vinylmethyldiacetoxy-silane, vinylbis(trimethylsiloxy)silane, vinyldimethoxyethoxysilane, alkyltriethoxysilane, alkyltriethoxysilane and allyltris(trimethylsiloxy)silane, 3-acryloxypropyltris(trimethylsiloxy)silane, 3-acryloxypropyltriethoxysilane, acrylopropylmethyldimethoxysilane, 3-acryloxypropylethylbis(trimethylsiloxy)silane, 3-acryloxypropyidimethylethoxysilane, n-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, 3-methacryloxypropyltris(vinyldimethylsiloxy)silane, 3-methacryloxypropyltris(trimethylsiloxy)silane, 3-methacryloxypropyltris(methoxyethoxy)silane, 3-methacrypropyltrimethoxysilane, 3-meth-acryloxypropylpentamethyldisiloxane, 3-methacryloxypropylmethyidimethoxysilane, 3-methacrylpropylmethyidiethoxysilane, 3-methacryloxypropyidimethylmethoxysilane, 3-methacryloxypropyidimethylethoxysilane, 3-methacrylpropenyltrimethoxysilane, or 3-methacryloxypropylbis(trimethylsiloxy)methylsilane. 
     
     
       23. The method of  claim 18 , further comprising forming an impact-resistant primer coating onto the scratch-resistant coating. 
     
     
       24. The method of  claim 23 , wherein the impact-resistant primer coating is formed by curing a poly(meth)acrylic based composition or a polyurethane based composition. 
     
     
       25. The method of  claim 24 , wherein the compositions are latexes. 
     
     
       26. The method of  claim 24 , wherein the impact-resistant primer coating composition comprises an effective amount of a coupling agent which is a pre-condensed solution of an epoxyalkoxysilane and an unsaturated alkoxy silane. 
     
     
       27. The method of  claim 26 , wherein the epoxyalkoxysilane is γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylpentamethyldisiloxane, γ-glydicoxypropylmethyidiisopropenoxysilane, (γ-glycidoxypropyl)methyldiethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyidiisopropylethoxysilane, or (γ-glycidoxypropyl)bis(trimethylsiloxy)methylsilane. 
     
     
       28. The method of  claim 27 , wherein the unsaturated alkoxysilane is tris(2-methoxyethoxy)silane, vinyltrisisobutoxysilane, vinyltri-t-butoxysilane, vinyltriphenoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyidiethoxysilane, vinylmethyldiacetoxy-silane, vinylbis(trimethylsiloxy)silane, vinyldimethoxyethoxysilane, allyltriethoxysilane, alkyltriethoxysilane and allyltris(trimethylsiloxy)silane, 3-acryloxypropyltris(trimethylsiloxy)silane, 3-acryloxypropyltriethoxysilane, acrylpropylmethyldimethoxysilane, 3-acryloxypropylethylbis(trimethylsiloxy)silane, 3-acryloxypropyldimethylethoxysilane, n-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, 3-methacryloxytris(vinyldimethylsiloxy)silane, 3-methacryloxypropyltris(trimethylsiloxy)silane, 3-methacryloxypropyltris(methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl-pentamethyldisiloxane, 3-methacryloxypropyl-methyidimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyl-dimethylmethoxysilane, 3-methacryloxypropyidimethylethoxysilane, 3-methacryloxypropenyltrimethoxysilane, or 3-methacryloxypropylbis(trimethylsiloxy)methylsilane. 
     
     
       29. The method of  claim 1 , further comprising forming an additional SiO 2  layer onto the anti-reflecting coating and then forming a scratch-resistant coating onto said additional SiO 2  layer. 
     
     
       30. The method of  claim 29 , further comprising forming an impact resistant primer coating onto the scratch-resistant coating. 
     
     
       31. A mold part of a two-part mold having opposed optical surfaces intended to define therebetween a molding cavity, the optical surface of said mold part being coated with a hydrophobic top coat and an anti-reflecting coating onto said hydrophobic top coat, wherein the anti-reflecting coating comprises a stack of dielectric material layers of alternate high and low refractive indices, and the first dielectric material layer deposited on the hydrophobic top coat comprises a first sub-layer of dielectric material deposited by vacuum deposition and a second sub-layer of dielectric material deposited by ion assisted vacuum deposition. 
     
     
       32. The mold part of  claim 31 , wherein said mold part is made of a plastic material. 
     
     
       33. The mold part of  claim 32 , wherein the mold part is a flexible mold part. 
     
     
       34. The mold part of  claim 31 , wherein said first dielectric material is SiO 2 . 
     
     
       35. The mold part of  claim 31 , wherein the thickness of the first sub-layer ranges from 2 to 12 nm and the thickness of the second sub-layer ranges from 68 to 98 nm. 
     
     
       36. The mold part of  claim 31 , wherein the stack of dielectric material layers is a four layer SiO 2 /ZrO 2 /SiO 2 /ZrO 2  stack. 
     
     
       37. The mold part of  claim 31 , further comprising an additional SiO 2  layer onto the anti-reflecting coating for promoting adhesion to a scratch-resistant coating. 
     
     
       38. The mold part of  claim 37 , wherein said additional SiO 2  layer has a physical thickness ranging from 1 to 50 nm. 
     
     
       39. The mold part of  claim 31 , further comprising a scratch-resistant coating onto the anti-reflecting coating. 
     
     
       40. The mold part of  claim 39 , further comprising an impact-resistant primer coating onto the scratch-resistant coating. 
     
     
       41. The mold part of  claim 31 , wherein the hydrophobic top coat is made of a silicone or a fluorosilicone. 
     
     
       42. The mold part of  claim 41 , wherein the hydrophobic top coat has a thickness ranging from 2 to 15 nm. 
     
     
       43. The mold part of  claim 31 , wherein the mold part is made of a plastic material comprised of polycarbonates, polyamides, polyimides, polysulfones, copolymers of polyethylene terephtalate and polycarbonate, crystal polyethylene terephtalate, glass fiber reinforced polyethylene terephtalate and/or polynorbornenes. 
     
     
       44. The mold part of  claim 31 , further comprising a protective coating on the optical surface of the mold part.